Field-flow fractionation (FFF) is a suite of elution methods suitable for the separation and sizing of macromolecules and particles 1. It relies on the combined effects of an applied force interacting with sample components and the parabolic velocity profile of carrier fluid in the channel. For this to be effective, the channel is unpacked and the flow must be under laminar conditions. Field or gradients that are commonly used in generating the applied force are gravity, centrifugation, fluid flow, temperature gradient, and electrical and magnetic fields. Each field or gradient produces a different subtechnique of FFF, which separates samples on the basis of a particular property of the molecules or particles.